Eccentric screw pump

ABSTRACT

The present invention relates to an eccentric screw pump ( 1 ) comprising an eccentric screw ( 5 ) and an elastic element ( 4 ) surrounding the latter as well as a drive device, wherein the eccentric screw ( 5 ) or the elastic element ( 4 ) surrounding the latter comprises a magnetic/magnetisable part ( 8 ) so that force transmission between the drive device and the eccentric screw ( 5 ) or the elastic element ( 4 ) is exclusively effected via magnetic field forces and wherein a magnetic/magnetisable part ( 8 ) of the eccentric screw ( 5 ) or the elastic element ( 4 ) required for the drive is not in contact with the fluid to be delivered, more preferably protected from direct contact with the fluid with a plastic covering.

The present invention relates to an eccentric screw pump for fluids.

From DE 10 2004 038 686 B3 a generic eccentric screw pump with a stator and a rotor running therein as well as a drive motor for driving the rotor is known. The rotor of the drive motor is rigidly connected with the rotor and runs on an eccentric orbit within a cylindrical pot. A rotational moment to drive the rotor is generated by means of a stator winding.

From DE 43 13 442 A1 a fluid pump operating according to the displacement principle with a stator consisting of an elastomer is known which is provided with a continuous hollow space in longitudinal direction. This hollow space in the un-deformed state of the stator is limited by two flat lateral surfaces and two semi-cylindrical end faces. In the stator, a motor provided with a round thread is arranged which can rotate relative to the stator wherein the hollow space of the stator and the round thread of the rotor are matched to each other in such a manner that the stator can only be deformed in a plane, namely in a plane perpendicularly to the lateral walls of the hollow space. During the rotation of the rotor in the deforming stator chambers are thus created which are displaced from the suction side of the pump to the delivery side, thus pumping the fluid.

The present invention deals with the problem of stating an improved embodiment for an eccentric screw pump of the generic type which more preferably satisfies a very high hygiene standard.

According to the invention, this problem is solved through the subject of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea with an eccentric screw pump known per se, which comprises an eccentric screw, an elastic element surrounding said eccentric screw and a drive device, to realise contactless force transmission between the drive device and the eccentric screw or the elastic element exclusively via magnetic field forces. In the process, the eccentric screw pump can be designed so that the drive device optionally drives the eccentric screw or the elastic element surrounding the latter in a contactless manner, wherein the eccentric screw or the elastic element then optionally comprise a magnetisable or magnetic part through which the magnetic field forces can be transmitted by the drive device. The magnetic or magnetisable part of the eccentric screw or the elastic element are preferentially designed as magnetic or magnetisable core and covered by a covering so that the magnetisable part is not in direct contact with the fluid to be delivered. With the eccentric screw pump according to the invention a pump is created which is extremely light and consequently hygienically cleanable since more preferably undercuts shaft lead-throughs, etc. in which for example germs can settle, are avoided. The eccentric screw pump is preferentially so designed that all of its components after the disassembly of a pump head can be individually and easily cleaned even by a simple user and not only by a trained and well-versed service technician. Through the simple construction and the low number of parts as well as low assembly complexity, the eccentric screw pump can be disassembled and cleaned even by a normal user, wherein more preferably the result of the cleaning can be visually verified by the user since—as mentioned above—the dead spaces that exist at present in eccentric screw pumps of this type will no longer exist.

In an advantageous further development of the solution according to the invention the drive device is designed as a coil. A coil of this type can for example be arranged axially adjacent or radially surrounding the eccentric screw pump or the elastic element, as a result of which a high level of design freedom with regard to the arrangement and configuration of the drive device can be created. In contrast with an electric drive device with magnetic force transmission merely between a rotor of the drive device and the eccentric screw or the elastic element, the coil itself does not require any rotating elements as a result of which it operates not only cost-effectively, but also with extremely low wear.

Additional, important features and advantages of the invention are obtained from the subclaims, from the drawings and from the corresponding figure description by means of the drawings.

It is to be understood that the features mentioned above and yet to be explained below cannot only be used in the respective combination stated but also in other combinations or standing alone, without leaving the scope of the present invention.

Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference symbols refer to identical or similar or functionally identical components.

Here it shows, in each case schematically,

FIG. 1 an eccentric screw pump according to the invention in exploded view,

FIG. 2 a sectional view through an eccentric screw pump according to the invention.

According to FIG. 1, an eccentric screw pump 1 according to the invention comprises a housing 2 with an inlet and outlet 3. A stator 4 designed as elastic element and an eccentric screw 5 rotatably mounted therein are at least partially arranged within the housing 2. These are held in the housing 2 via a housing lid 6. The components 2, 4, 5 and 6 together form a so-called pump head which is arranged in a housing-like receptacle 7. The eccentric screw 5 according to the embodiments shown in FIG. 1 and 2 comprises a magnetisable or magnetic drive disc 8 which is in force-transmitting contact via a face plate 9 with a likewise magnetic or magnetisable drive disc 8′ of a drive device which is not shown. Here, according to the shown embodiments, exclusively the eccentric screw 5 is driven by the drive device in a contactless manner while it is also conceivable that the drive device drives the elastic element 4 by means of magnetic field forces while the eccentric screw 5 forms the actual stator element.

According to the invention, force transmission between the drive device and the eccentric screw 5 or the elastic element 4 is exclusively effected via magnetic field forces, i.e. more preferably not through a shaft which would for example break through the receptacle 7 and thus create areas that are difficult to clean. More preferably a pump can be created with the eccentric screw pump 1 according to the invention and its contactless drive which has no dead spaces or areas that are difficult to clean, in which germs can settle. The resultant particularly hygienic operation can be additionally increased in that a magnetic/magnetisable part of the eccentric screw 5 or the elastic element 4 required for the drive according to FIG. 1 and 2, i.e. the drive disc 8, is no longer in contact with the fluid to be delivered and more preferably protected from direct contact with the fluid by means of a plastic covering. The magnetic or magnetisable drive disc 8 thus merely forms a magnetic or magnetisable core which is covered by the plastic covering.

For the force transmission between the drive device and the eccentric screw 5 an electric magnet or a permanent magnet can for example be provided while it is also conceivable that the drive device has no rotating elements at all, i.e. more preferably no rotating magnetic or magnetisable drive disc 8′, but for example is designed as a coil. With a drive device designed as a coil, particularly low noise and low maintenance operation of the eccentric screw pump 1 is possible.

As already mentioned at the outset, the drive device can optionally act on the eccentric screw 5 or the elastic element 4 surrounding the latter, wherein in the latter case the elastic element 4 likewise comprises a magnetic or magnetisable part, more preferably a magnetic or magnetisable core.

In general the eccentric screw pump 1 according to the invention can be part of a coffee maker or a device for dosing or dispensing liquids and/or foam more preferably for the dosing or dispensing of milk froth. In addition it is also conceivable that the eccentric screw pump 1 is part of a device for the dosing or the dispensing of sauces and/or pasty foods for example mustard, mayonnaise or ketchup.

Obviously not only the embodiments of the eccentric screw pump 1 shown according to FIG. 1 and FIG. 2 are enclosed by the inventive idea but also other embodiments wherein contactless drive of the eccentric screw 5 or the elastic element 4 takes place and wherein the eccentric screw pump 1 because of the contactless drive can be disassembled and thus cleaned particularly easily and simply. More preferably, the receptacle 7 can also be embodied entirely without undercuts and blind holes so that after disassembly of the pump head formed of parts 2, 4, 5 and 6 only largely flat surfaces which are easy to clean remain. Obviously, the eccentric screw pump 1 according to the invention can also have a suitable device which makes it possible to overcome the magnetic forces between the drive disc 8′ and the drive disc 8 during the assembly, wherein this is most easily realised for example through a thread with a large pitch on the housing 2. Through the simple construction and the simultaneously low number of parts of the eccentric screw pump 1 according to the invention it can also be cleaned by conventional users without problems, while the cleaning result can also be visually verified because of the simplified assembly. In addition to this, the eccentric screw pump 1 according to the invention can be manufactured cost-effectively and allows the user to see the complete media path of the fluid to be delivered. In general, the elastic element 4 can assume additional sealing functions, more preferably to seal the housing 2 against the receptacle 7. Particularly practical here is a sealing function of the housing 2 towards the housing lid 6. 

1. A food-based device, comprising: an eccentric screw pump for food-based fluids.
 2. The food-based device according to claim 1, wherein: i. the eccentric screw pump comprises an eccentric screw and an elastic element surrounding the eccentric screw, and a drive device, ii. at least one of the eccentric screw and the elastic element surrounding the eccentric screw comprises one of a magnetic and a magnetisable part so that force transmission between the drive device and the selected one of the eccentric screw and the elastic element is generally exclusively effected via magnetic field forces, and iii. the selected one of the magnetic and magnetisable part of the selected at least one of the eccentric screw and the elastic element required for the drive is not in contact with the fluid to be delivered.
 3. The food-based device according to claim 1, wherein at least one of an electric magnet and a permanent magnet are provided which generates a magnetic field forces required for force transmission.
 4. The food-based device according to claim 1, wherein a housing, the elastic element that is a stator, the eccentric screw and a housing lid together form a pump head which is arranged in a receptacle, wherein the receptacle is designed without undercuts and blind holes so that after disassembly of the pump head only largely flat surfaces which are easy to clean remain.
 5. The food-based device according to claim 2, wherein the drive device comprises a magnetic drive disc which is arranged axially adjacent to at least one of the selected magnetic and magnetisable drive disc of the selected at least one elastic element and the eccentric screw.
 6. (canceled)
 7. (canceled)
 8. The food-based device according to claim 2, wherein the selected one of the magnetic and magnetisable part of the selected one of the eccentric screw and the elastic element required for the drive is protected from direct contact with fluid with a plastic covering.
 9. The food-based device according to claim 2, wherein at least one of an electric magnet and a permanent magnet are provided which generates a magnetic field forces required for force transmission.
 10. The food-based device according to claim 2, wherein a housing, the elastic element that is a stator, the eccentric screw and a housing lid together form a pump head which is arranged in a receptacle, wherein the receptacle is designed without undercuts and blind holes so that after disassembly of the pump head only largely flat surfaces which are easy to clean remain.
 11. The food-based device according to claims 3, wherein the drive device comprises a magnetic drive disc which is arranged axially adjacent to one of the selected magnetic and magnetisable drive disc of the selected elastic element and the eccentric screw.
 12. The food-based device according to claim 3, wherein a housing, the elastic element that is a stator, the eccentric screw and a housing lid together form a pump head which is arranged in a receptacle, wherein the receptacle is designed without undercuts and blind holes so that after disassembly of the pump head only largely flat surfaces which are easy to clean remain.
 13. The food-based device according to claim 4, wherein the drive device comprises a magnetic drive disc which is arranged axially adjacent to one of the selected magnetic and magnetisable drive disc of the selected elastic element and the eccentric screw.
 14. A method of dosing and dispensing a food-based fluid that is at least one of a sauce and a pasty food, comprising: providing a device with an eccentric screw pump; and using the device to dose and dispense the at least one sauce and pasty food.
 15. A method of dosing and dispensing at least one of a fluid-based fluid and a foam, comprising: providing a device with an eccentric pump; and using the device to dose and dispense the at least one fluid and foam.
 16. The method as recited by claim 15, wherein the at least one fluid and foam is a milk froth.
 17. The device according to claim 1, wherein the food-based fluid is coffee and the food-based device is a coffee maker.
 18. The device according to claim 1, wherein the food-based fluid is a sauce
 19. The device according to claim 1, wherein the food-based fluid is a pasty food. 